Electrophoresis concepts

In particular, in polar solvents, the surface of a colloidal particle tends to be charged. As will be discussed in section C2.6.4.2, this has a large influence on particle interactions. A few key concepts are introduced here. For more details, see [32] (eh 13), [33] (eh 7), [36] (eh 4) and [34] (eh 12). The presence of these surface charges gives rise to a number of electrokinetic phenomena, in particular electrophoresis. 

Immunoelectrophoretic Techniques. The technique of gel electrophoresis has been successfully combined with immunological techniques in order to further evaluate molecules. Specifically, the concept of double immunodiffusion as described in 1948 (57) and that of single-radial immunodiffusion described in 1963 (58) have been further developed for use with electrophoresis in both the clinical and research setting. 

Process Concept The application of a direct elecdric field of appropriate polarity when filtering should cause a net charged-particle migration relative to the filter medium (electrophoresis). The same direct electric field can also be used to cause a net fluid flow relative to the pores in a fixed filter cake or filter medium (electroosmosis). The exploitation of one or both of these phenomena form the basis of conventional electrofiltration. 

Despite much excitement in the 1990s over the potential for microfluidics and nanoengineering to revolutionize HTS, there have been few commercially viable systems that embody the concept. Most notable is the Caliper capillary electrophoresis... 

With the study of the migration of hydrogenium ions (H ) in a phenolphthalein gel by Lodge in 1886 and the description of the migration of ions in saline solutions by Kohlraush in 1897, a basis was set for the development of a new separation technique that we know today as electrophoresis. Indeed, several authors applied the concepts introduced by Lodge and Kohlraush in their methods and when Arne Tiselius reported the separation of different serum proteins in 1937, the approach called electrophoresis was recognized as a potential analytical technique. Tiselius received the Nobel Prize in Chemistry for the introduction of the method called moving boundary electrophoresis. ... 

Isoelectric points are useful concepts for the separation and purification of amino acids and proteins using electrophoresis. Under the influence of an electric field, compounds migrate according to their overall charge. As we have just seen for amino acids, this very much depends upon the pH of the solution. At the isoelectric point, there will be no net charge, and, therefore, no migration towards either anode or cathode. 

Anderson NL, Anderson NG (1998) Proteome and proteomics new technologies, new concepts, and new words. Electrophoresis 19 1853-1861... 

Hjelmeland, L.M., Chrambach, A. (1981). Electrophoresis and electrofocusing in detergent containing media A discussion of basic concepts. Electrophoresis, 2, 1-11. 

The Effect of SDS Micelle on the Rate of a Reaction, J. Chem. Ed. 1992, 69, 1024 C. P. Palmer, Demonstrating Chemical and Analytical Concepts Using Electrophoresis and Micellar Electrokinetic Chromatography, J. Chem. Ed 1999, 76, 1542. 

J. Palmer, N. J. Munro, and J. P. Landers, A Universal Concept for Stacking Neutral Analytes in Micellar Capillary Electrophoresis, Anal. Chem. 1999, 71, 1679 J. Palmer, D. S. Burji, N. J. Munro, and J. P. Landers, Electrokinetic Injection for Stacking Neutral Analytes in Capillary and Microchip Electrophoresis, Anal. Chem. 2001, 73, 725 J. P. Quirino, S. Terabe, and... 

R. Boyer, Concepts in Biochemistry (1999). Brooks/Cole (Pacific Grove, CA) pp. 104-105. Introduction to electrophoresis. 

Thus electrophoretic separation of proteins on PNIPAAm gel can be achieved, and the proteins can be recovered from the gel. However, the substantial technical difficulties we encountered made our vision of a simple swap of PNIPAAm gel for polyacrylamide gel in standard procedures impossible to realize. Thus, we discontinued further work on this project. However, the concept might still find use in cases of routine preparative gel electrophoresis where the problems and expense of solute recovery as described earlier were significant enough to warrant the developmental work required to make the PNIPAAm process practical. 

Another recent development is the advent of pulse amperometry in which the potential is repeatedly pulsed between two (or more) values. The current at each potential or the difference between these two currents ( differential pulse amperometry ) can be used to advantage for a number of applications. Similar advantages can result from the simultaneous monitoring of two (or more) electrodes poised at different potentials. In the remainder of this chapter it will be shown how the basic concepts of amperometry can be applied to various liquid chromatography detectors. There is not one universal electrochemical detector for liquid chromatography, but, rather, a family of different devices that have advantages for particular applications. Electrochemical detection has also been employed with flow injection analysis (where there is no chromatographic separation), in capillary electrophoresis, and in continuous-flow sensors. 

Many of these microsystems have been described, but capillary electrophoresis (CE) microchips seem to be the most widely developed. The concept of p-TAS was proposed by Manz et al. in 1990 [1] and 2 years later, electrophoresis in planar chips was successfully integrated and its use demonstrated using silicon and glass substrates [2,3]. This area of miniaturised analysis systems has grown rapidly, as is shown in two complete revisions by Manz et al. [4,5], the first dealing with theory and technology and the second one with analytical standard operations and applications, and the development continues exponentially. 

The discovery of semiconductor integrated circuits by Bardeen, Brattain, Shockley, Kilby, and Noyce was a revolution in the micro and nano worlds. The concept of miniaturization and integration has been exploited in many areas with remarkable achievements in computers and information technology. The utility of microchips was also realized by analytical scientists and has been used in chromatography and capillary electrophoresis. In 1990, Manz et al. [1] used microfluidic devices in separation science. Later on, other scientists also worked with these units for separation and identification of various compounds. A proliferation of papers has been reported since 1990 and today a good number of publications are available in the literature on NLC and NCE. We have searched the literature through analytical and chemical abstracts, Medline, Science Finder, and peer reviewed journals and found a few thousand papers on chips but we selected only those papers related to NLC and NCE techniques. Attempts have been made to record the development of microfluidic devices in separation science. The number of papers published in the last decade (1998-2007) is shown in Fig. 10.1, which clearly indicates rapid development in microfluidic devices as analytical tools. About 30 papers were published in 1998 that number has risen to 400 in... 

Most theoretical treatments of the gel electrophoresis of DNA molecules are based upon de Gennes (1971) concept of reptation. The migration of the nucleic acid is considered to occur in a tube formed by the polymer matrix of the gel, through which the DNA migrates rather like a... 

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